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HBase, mail # user - Is hadoop 1.0.0 + HBase 0.90.5 the best combination for production cluster?


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Re: Is hadoop 1.0.0 + HBase 0.90.5 the best combination for production cluster?
Bryan Keller 2012-02-17, 21:48
I was thinking (wrongly it seems) that having the region server read directly from the local file system would be faster than going through the data node, even with sequential access.

On Feb 17, 2012, at 1:28 PM, Jean-Daniel Cryans wrote:

> On Fri, Feb 17, 2012 at 1:21 PM, Bryan Keller <[EMAIL PROTECTED]> wrote:
>> I have been experimenting with local reads. For me, enabling did not help improve read performance at all, I get the same performance either way. I can see in the data node logs it is passing back the local path, so it is enabled properly.
>
> I was surprised when I read this until I saw this:
>
>>
>> Perhaps the benefits of local reads are dependent on the type of data and the workload? In my test I'm scanning through the entire table via a map reduce job. It's a wide table with maybe 20k columns per row on average. I have scanner caching set to 10.
>
> It's definitely not going to help make sequential reads faster.
>
>>
>> My read performance is about 10% of the disk max read throughput, i.e. my disks can get 100 mb/sec tested with hdparm and scan performance is about 10 mb/sec. Not too bad I suppose.
>
> Maybe you're not pushing it enough?
>
> J-D